If your ignition switch is worn, the key when in the #2 position may not let the blower engage. Try turning the key ever so slightly counterclockwise and see if the blower engages.

Yea, yea, I know if it's a diesel it's not the ignition switch......

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles